Not many public figures have done as much for sharks as the late Canadian filmmaker Rob Stewart, who dedicated his life to helping save the misunderstood aquatic beasts.

His latest and last film, Sharkwater Extinction, is a cinematic eulogy of Stewart, who stood up to governments and politicians, confronting them about their outdated and often cruel shark-fishing and “finning” practices. He was involved in the movie’s production right up until his passing in January of last year.

The movie switches gears entirely after Stewart’s death: the first half continues the work started up in his first and second documentaries, 2006’s Sharkwater and 2012’s Revolution, and after his devastating drowning, it turns into a tribute to the man. Just like the original docs, Sharkwater Extinction is harrowing and frustrating. Once again, we see how millions of sharks are needlessly killed each year for their fins, and how often any action against the practice is futile. Stewart was one of the rare few who managed to make an impact.

Global News spoke with Brock Cahill, a very close friend of Stewart’s and founder of SeaChange Agency, about making the movie and what’s being done to continue Stewart’s legacy.

Global News: For those unaware, what’s your relationship to Rob and this movie?Brock Cahill: For Extinction, we developed strategies, thought processes and figured out together where we wanted to go with the film. I was his right-hand man, and Robbie always called me “our ninja,” so…

What sorts of challenges did you face? After Rob’s passing, it must’ve been hard to finish up the movie.
Oh man, was it ever. The weight, from an emotional standpoint, . Having to forge forward without my buddy was f**king tragic. Without his creative mindset and leadership, it became much more challenging to figure out strategies. But somehow, with his folks and everybody else on the team, we’re here with the film.

What are you doing to ensure that Rob’s legacy continues on?
One would be to make sure we continue his energetic and positive influence on the world, helping to ignite and inspire new people to the cause. Also, on another scale, we want to save sharks and save oceans — that’s all there is to it. All life on this planet hinges on the survival of sharks. Most people don’t recognize that, and it’s our job to ensure they do.

WATCH BELOW: The legacy of ‘Sharkwater’ filmmaker Rob Stewart

One statistic repeated in the film is 150 million sharks are killed every year. Is that staggering number accurate?
Yes. The estimates are between 100 and 150 million per year, but note that they always err on the side of conservatism, so I wouldn’t doubt that there are more than that . Lots are probably unaccounted for. No species can survive that kind of pressure. They’re on the brink. We have to save the ones we have left.

In the film, there’s a lot of footage of Rob hugging and petting the sharks. Were you able to do that as well?
Yeah, I’m also in that same boat. It’s wonderful. They’re very intriguing animals, and super energetic. Robbie and I found ways to communicate with them. You can read energy. You can find a way of connecting, and it’s been one of my favourite things in the world. Rob and I actually developed that vocabulary together, being in the water so much. He was the only other human (besides me) who’s learned that language, but I intend to teach a whole lot more people so we can start speaking it.

Rob Stewart as seen in Sharkwater Extinction.

eOne Films/Will Allen

What can everyday people do to help sharks and ocean life as a whole?
One thing people can do is become an informed consumer. Sharks aren’t only being taken for their fins, but for a lot of other products. For example, their liver oil is being taken for cosmetics, for moisturizers. We need to be aware of what’s going into the products we use. It’s also going into things like pet food and fish meal; it’s also being fed to us!

There’s a good chance you might be eating shark. Close to 50 per cent of seafood is mislabeled. “Shark” at this point has about 18 names in English and a bunch more in Spanish. You don’t know you’re eating a super-predator. “Oceaniac whitefish,” “flake” or “rock salmon” are all different kinds of sharks. We need to be aware and make different choices. We need to insist that governments, agencies and organizations end the trade of shark products. All of our survival hinges upon it.